B.: You see, there exist several concepts of the origin of the solar system. Some of them suggest that the sun and the planets originated at the same time from a tremendous cloud of gas, mostly hydrogen and cosmic dust.

A.: And what do other hypotheses suggest?

B.: Other hypotheses suggest that the planets are younger than the sun, that first the center of the cloud condensed and became a star – the sun, and then various densities gave birth to the planets.

A.: I see.

B.: But it must be said that there is still no generally accepted theory to explain how and when the sun and the planets formed.